feat: add Splom + Parcats trace types

Add typed scatter-plot-matrix (splom) and parallel-categories (parcats)
traces following the established trace-struct recipe.

- Register PlotType::{Splom, Parcats} (serialize to "splom"/"parcats"),
  re-export modules + traces from traces/mod.rs and lib.rs.
- All attributes verified against bundled plotly.js 3.7.0 schema.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Andrei Gherghescu <8067229+andrei-ng@users.noreply.github.com>

Author: 2 people

CHANGELOG.md

@@ -14,8 +14,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - [[#414](https://github.com/plotly/plotly.rs/issues/414)] Add `DensityMap` (MapLibre `map` subplot) trace type — density heatmaps with full color-scale and hover support
 - [[#417](https://github.com/plotly/plotly.rs/issues/417)] Add `ScatterMap` (MapLibre `map` subplot) trace type — the modern counterpart to `ScatterMapbox`
 - [[#418](https://github.com/plotly/plotly.rs/issues/418)] Add native point clustering to `ScatterMap` via a `Cluster` option
-- [[#421](https://github.com/plotly/plotly.rs/pull/421)] Backfill trace attributes on trace types to bring them to parity with  plotly.js 3.7 
+- [[#421](https://github.com/plotly/plotly.rs/pull/421)] Backfill trace attributes for trace types to bring them to parity with  plotly.js 3.7 
 - [[#422](https://github.com/plotly/plotly.rs/issues/422)] Add `Indicator`, `Histogram2d`, `Icicle` trace types 
+- [[#425](https://github.com/plotly/plotly.rs/issues/425)] Add `Splom` and `Parcats` trace types (scatter-plot matrix and parallel categories) 
 
 ### Changed
 

plotly/src/common/mod.rs

@@ -231,7 +231,9 @@ pub enum PlotType {
     Indicator,
     Mesh3D,
     Ohlc,
+    Parcats,
     Sankey,
+    Splom,
     Surface,
     DensityMapbox,
     DensityMap,

plotly/src/lib.rs

@@ -61,15 +61,15 @@ pub use plot::{Plot, Trace, Traces};
 // Also provide easy access to modules which contain additional trace-specific types
 pub use traces::{
     box_plot, choropleth, choropleth_map, contour, density_map, heat_map, histogram, histogram2d,
-    icicle, image, indicator, mesh3d, sankey, scatter, scatter3d, scatter_map, scatter_mapbox,
-    sunburst, surface, treemap, violin,
+    icicle, image, indicator, mesh3d, parcats, sankey, scatter, scatter3d, scatter_map,
+    scatter_mapbox, splom, sunburst, surface, treemap, violin,
 };
 // Bring the different trace types into the top-level scope
 pub use traces::{
     Bar, BoxPlot, Candlestick, Choropleth, ChoroplethMap, Contour, DensityMap, DensityMapbox,
-    HeatMap, Histogram, Histogram2d, Icicle, Image, Indicator, Mesh3D, Ohlc, Pie, Sankey, Scatter,
-    Scatter3D, ScatterGeo, ScatterMap, ScatterMapbox, ScatterPolar, Sunburst, Surface, Table,
-    Treemap, Violin,
+    HeatMap, Histogram, Histogram2d, Icicle, Image, Indicator, Mesh3D, Ohlc, Parcats, Pie, Sankey,
+    Scatter, Scatter3D, ScatterGeo, ScatterMap, ScatterMapbox, ScatterPolar, Splom, Sunburst,
+    Surface, Table, Treemap, Violin,
 };
 
 pub trait Restyle: serde::Serialize {}

plotly/src/traces/mod.rs

@@ -16,6 +16,7 @@ pub mod image;
 pub mod indicator;
 pub mod mesh3d;
 mod ohlc;
+pub mod parcats;
 pub mod pie;
 pub mod sankey;
 pub mod scatter;
@@ -24,6 +25,7 @@ pub mod scatter_geo;
 pub mod scatter_map;
 pub mod scatter_mapbox;
 mod scatter_polar;
+pub mod splom;
 pub mod sunburst;
 pub mod surface;
 pub mod table;
@@ -45,6 +47,7 @@ pub use icicle::Icicle;
 pub use indicator::Indicator;
 pub use mesh3d::Mesh3D;
 pub use ohlc::Ohlc;
+pub use parcats::Parcats;
 pub use pie::Pie;
 pub use sankey::Sankey;
 pub use scatter::Scatter;
@@ -53,6 +56,7 @@ pub use scatter_geo::ScatterGeo;
 pub use scatter_map::ScatterMap;
 pub use scatter_mapbox::ScatterMapbox;
 pub use scatter_polar::ScatterPolar;
+pub use splom::Splom;
 pub use sunburst::Sunburst;
 pub use surface::Surface;
 pub use table::Table;